Complete and partial restriction enzyme digests of genomic DNA will be analyzed by PFGE to map the known DNA markers linked to the gene for cystic fibrosis. These techniques will be used to identify large DNA fragments that span the chromosomal site of the cystic fibrosis gene. These fragments will be used to prepare cDNA libraries corresponding to all mRNAs encoded by DNA of the size of the fragments. Further screening of the cDNA libraries will be performed to isolate those clones that are encoded on chromosome 7. Each such clone will be compared from cystic fibrosis and normal pancreatic and nasal polyp tissue. Potential mutations will be identified and DNA from a group of diseased subjects and phenotypically normal individuals will be evaluated to confirm the association of the mutation with the disease.